Compressor shaft seal

ABSTRACT

A seal for a compressor for sealing a shaft comprises a first seal part with a sealing edge which is provided on a circular cylindrical surface along a line which deviates from a circular shape and which is closed in itself in the peripheral direction for adjoining and sealing the shaft, and a second seal part with a sealing section which is intended to adjoin the shaft and which is hollowly cylindrical when it adjoins properly with the inside surface which comprises a return structure for a fluid.

This application is a divisional of U.S. application Ser. No. 11/760,072filed on Jun. 8, 2007 and claims priority to German Application no. 102006 026 812.1 filed on Jun. 9, 2006, the entire content of both ofwhich is incorporated herein by reference.

TECHNICAL FIELD

The subject matter disclosed herein generally pertains to a seal. Morespecifically, the subject matter relates to a seal used in a compressorfor sealing a shaft.

BACKGROUND DISCUSSION

In the automotive domain, compressors in air conditioning systems areoften driven unencapsulated via a shaft. The shaft penetrates thecompressor housing and requires sealing against the escape of coolantand lubricating oil from the compressor interior to the atmosphere. Dueto the relative speeds and operating pressures, an elastomer sealingedge of such a seal is sometimes supported by a PTFE washer using itsgood sliding properties, by which overly strong deformation of theelastomer sealing edge and premature wear are avoided. The indicatedPTFE washers are held by virtue of being clamped between a vulcanizedsealing element and an additional metallic support ring. To shield theprocess pressure on the PTFE contact surface to the shaft, othermetallic support elements are used in the packing. In this regard, ametallic support element is vulcanized into the packing such that with ahollow cylindrical region it shields the PTFE contact surface againstthe process pressure and for the most part supports the elastomersealing edge.

SUMMARY

A compressor apparatus comprises: a housing containing a lubricant and acoolant; a rotatable shaft penetrating the housing; and a seal adjoiningthe shaft to seal against leakage of the lubricant and the coolant sothat the lubricant and the coolant do not leak to outside the housing.The seal comprises: a first seal part possessing a cylindrical sealingedge adjoining the seal and seal the shaft, the sealing edge extendingalong a line which deviates from a circular shape and which is closed initself in a peripheral direction, the line along which the sealing edgeextends is wavy, comprising several arcs; and a second seal part with asealing section which is adapted to adjoin the shaft and which ishollowly cylindrical when the sealing section adjoins properly with anoutside surface of the shaft. The sealing section comprises a returnstructure for returning a fluid, the sealing section configured toextend along the outside surface of the shaft between the first sealpart and the shaft when the sealing section properly adjoins the outsidesurface of the shaft.

Because the sealing edge is provided on a circular cylindrical surfaceand extends along a line which deviates from a circular shape (e.g., awavy or sinusoidal shape) and which is closed in itself in theperipheral direction, the relative motion between the shaft and thesealing edge oils the shaft surface, by which advantageously even with alack of lubrication a lubricating film forms under the sealing edge andthus wear due to abrasion is prevented. In addition, the tightness ofthe seal is supported by the return structure of the second seal part.The result is a seal with relatively high wear resistance.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

Additional features and details associated with the disclosed sealingelement will become more apparent from the embodiments of the sealingelement described below and illustrated in the following drawingfigures.

FIG. 1 is a lengthwise cross-sectional view through the upper region ofa seal according to one disclosed embodiment.

FIG. 2 is a lengthwise cross-sectional view through the upper region ofa seal according to another disclosed embodiment.

FIG. 3 is a lengthwise cross-sectional view through the upper region ofa seal according to an additional disclosed embodiment.

FIG. 4 is a lengthwise cross-sectional view through the upper region ofa seal according to a fourth disclosed embodiment.

FIG. 5 is a lengthwise cross-sectional view through the upper region ofa seal according to a fifth disclosed embodiment.

FIG. 6 is a lengthwise cross-sectional view through the upper region ofa seal according to a sixth disclosed embodiment.

DETAILED DESCRIPTION

FIG. 1 illustrates, in lengthwise cross-section, the upper half of aseal as disclosed herein, with the seal being shown as if it wereproperly located on the shaft of a compressor which is designed to turnand which is to be sealed. A portion of the shaft S is shown in FIG. 1for illustrative purposes. At the right side of the seal, for example,there extends the interior of the compressor which is properlypressurized and which is filled by a refrigerant and/or a lubricant. Theseal prevents the refrigerant and/or lubricant from penetrating into theleft space, for example the atmospheric side, and also prevents dirt orthe like from penetrating from the left space (atmospheric side) intothe right space which is filled by the refrigerant and/or lubricant.

From an overall perspective, the seal comprises three sections, an outerhollow cylindrical section 12, a ring-like or perforated disk-likesection 14, and an inner hollow cylindrical section 16. The disk-likesection 14 is referred to as a perforated section because of the centralhole in the disk 14 as shown in FIG. 3 (and FIG. 5 discussed below). Theoutside surface of the outer hollow cylindrical section 12 is designedto adjoin a correspondingly made opening of a compressor housing. Aportion of the housing is schematically shown in FIG. 1 (identified asH) for illustrative purposes, it being understood that in use, thehousing would typically deform the corrugations on the outer surface ofthe outer hollow cylindrical section 12 (first seal part). The rightaxial end of this outer hollow cylindrical section 12 to the inside isconnected to the ring-like or perforated disk-like section 14 whoseinside edge is connected to the inner hollow cylindrical section 16which extends to the right side. In the illustrated embodiment, theouter hollow cylindrical section 12 extends in the axial direction, theperforated disk-like section 14 extends radially inwardly from the endof the outer hollow cylindrical section 12, and the inner hollowcylindrical section 16 extends in the axial direction from the end ofthe disc-like section 24. As illustrated, the free end portion of theinner hollow cylindrical section 16 is angled slightly radiallyinwardly.

The seal comprises a first seal part 1 of elastomer material, a secondseal part 2 of polytetrafluorethylene (PTFE), and a stiffening part 4.Thus, the first seal part 1 and the second seal part 2 are made ofdifferent materials, and the stiffening part 4 is made of a stilldifferent material, preferably metal. The stiffening part 4 and thefirst seal part 1 are connected to one another by vulcanization of thefirst seal part 1 onto the stiffening part 4. In the perforateddisk-like section 14 of the seal, a radially extending surface region ofthe second seal part 2 is joined in a chemically-tight manner, forexample by vulcanization, to the corresponding surface region of thefirst seal part 1. Advantageously the secure interlocking between thefirst and second seal part 1 and 2 reliably prevents the second sealpart 2 from being turned up by the process pressure prevailing on theright side in the direction to the left side.

In the outer hollow cylindrical section 12 of the seal, the hollowcylindrical region of the stiffening part 4 is surrounded by a likewisehollow cylindrical region of the first seal part 1. In the perforateddisk-like section 14 of the seal, a perforated disk-like region of thestiffening part 4 is surrounded both to the left and also the right sideby the first seal part 1. In the inner hollow cylindrical section 16 ofthe seal is an inner hollow cylindrical region of the stiffening part 4which is essentially surrounded on all sides by the first seal part 1,with the first seal part 1 in the section 16 being made with a sealingedge 7 which is designed to adjoin the shaft and seal it. In thisconnection, as shown in FIG. 1, the sealing edge 7 runs on a cylindricalsurface (circular cylindrical surface) along a wavy line which deviatesfrom a circular shape and which is closed in itself in the peripheraldirection. The wavy shape of the sealing edge comprises a number ofsuccessively arranged arcs formed by a zig-zag, sinusoidal, oscillatingor otherwise wavy shape. With this wavy configuration of the sealingedge, the relative motion between the shaft and the sealing edge 7 oilsthe shaft surface, by which advantageously, even with a lack oflubrication, a lubricating film forms under the sealing edge 7 and thuswear due to abrasion is prevented. In other embodiments, the line canalso be made of several arcs, zig-zag or other than a sinusoidal wavyform as illustrated.

With proper seal installation, in the inner hollow cylindrical section16 of the seal, a hollow cylindrical sealing section of the second sealpart 2 extends which is intended to adjoin the shaft and which isconnected to the first seal part 1. The second seal part 2 isdimensioned such that with proper seal installation, the hollowcylindrical sealing section of the second seal part 2 does not come intoconflict with the sealing edge 7 of the first seal part 1. The hollowcylindrical sealing section of the second seal part 2 on the innersurface side is provided with a return structure, in the form of ahelical groove 8, in order to achieve a return action to the sealingedge side of lubrication and/or coolant films which may be present therewhen the shaft turns accordingly. Instead of the helical groove 8,alternative embodiments are possible including other single-thread ormultiple thread screw-like structures. The second seal part 2 canacquire or be provided with the groove-like return structure via hotstamping in a vulcanization process in which the second seal part 2 isdirectly chemically linked to the first vulcanized seal part 1.

The inner hollow cylindrical portion and also the perforated disk-likeregion of the stiffening part 4 shield the second seal part 2 againstthe process pressure which is present in the right space andadvantageously support the first seal part 1 for sealing contact of itssealing edge 7 with the shaft. The sealing edge 7 of the first seal part1 is supported by the second seal part 2 using its good slidingproperties, and excess deformation of the sealing edge 7 and prematurewear due to the relative speeds and operating pressures which arise areprevented.

FIG. 2 illustrates another embodiment, once again illustrating the sealin lengthwise cross-section through a seal according to the secondembodiment. The seal of FIG. 2 differs from that of FIG. 1 essentiallyin that the return structure on the inside surface of the hollowcylindrical sealing section of the second seal part 2′ has severalarc-shaped or sickle-shaped grooves 8′ which are distributed in theperipheral direction and have respective ends opening at the sealingedge side. The arc-shaped or sickle-shaped grooves are each configuredto possess a gradient increasing in absolute value in a direction towardor onto the sealing edge as shown in FIG. 2 (and other drawing figuressuch as FIGS. 4 and 5 which are described below in more detail). Thegrooves 8′ can be made so as to exhibit a groove-like (U-shaped orV-shaped) cross-sectional profile or a trapezoidal cross sectionalprofile, and begin in the axial end region of the hollow cylindricalseal section opposite the sealing edge side. Other aspects of the sealare the same as those described above in connection with the FIG. 1embodiment and so the description applies equally here. Comparable orcorresponding features or components in FIG. 2 are identified by thesame reference numbers, but with the addition of a prime (′) designationin FIG. 2.

FIG. 3 illustrates another embodiment of the seal and once againillustrates the upper region of the seal in lengthwise cross-section.The seal in this third embodiment differs from that of FIG. 2essentially in that the arc-shaped grooves 8″ start or proceed from agroove 9″ which runs peripherally in the form of a circular ring grooveand which is located on the axial end (i.e., the left end side) of thehollow cylindrical sealing section which is opposite the sealing edgeside. Other aspects of the seal are the same as those described above inconnection with the FIG. 2 embodiment and so the description appliesequally here. Comparable or corresponding features or components in FIG.3 are identified by the same reference numbers, but with the addition ofa double prime (″) designation in FIG. 3.

FIG. 4 illustrates a fourth embodiment of the seal and once againillustrates the upper region of the seal in lengthwise cross-section.The version of the seal shown in FIG. 4 differs from that of FIG. 2essentially in that the arc-shaped grooves 8′″ are provided in pairs,with the opposite direction of curvature and crossing one another.Advantageously a medium flowing to the left side in the crossing regionis deflected again to the right side by the crossings. In this way, thereturn structure, in a manner similar to the sinusoidal sealing edge 7′″acts in both directions of rotation of the shaft. Other aspects of theseal shown in FIG. 4 are the same as those described above in connectionwith the FIG. 2 embodiment and so the description applies equally here.Comparable or corresponding features or components of the embodimentshown in FIG. 4 are identified by the same reference numbers as in FIG.2, but with the addition of a triple prime (′″) designation in FIG. 4.

FIG. 5 illustrates a fifth version of the seal, once again illustratingthe upper region of the seal in lengthwise cross-section. The seal ofthis fifth embodiment differs from that of FIG. 4 essentially in that,similar to the seal of FIG. 3, the ends of the arc-shaped grooves 8″″start from a circular ring-like groove 9″″ which is located on the axialend of the hollow cylindrical sealing section which is opposite thesealing edge side. Other aspects of the seal shown in FIG. 5 are thesame as those described above in connection with the FIG. 4 embodimentand so the foregoing description applies equally here. Comparable orcorresponding features or components of the embodiment shown in FIG. 5are identified by the same reference numbers as in FIG. 4, but with theaddition of a quadruple prime (″″) designation in FIG. 5.

FIG. 6 illustrates a further embodiment of the seal, illustrating theupper region of the seal in lengthwise cross-section. The seal shown inFIG. 6 differs from that of the FIG. 2 embodiment essentially in that onthe axial end opposite the sealing edge side, the second seal part 2′″″is provided with another seal part 5′″″ of a gas diffusion-capablefabric, for example of formed fabric. This other seal part 5′″″ which islocated on the atmosphere side of the seal is securely joined to thesecond seal part 2′″″ and is constructed so that it touches the shaftand surrounds it, thus preventing penetration of solids into the sealingregion of the first and second seal part 1′″″ and 2′″″ from the airside. Due to the open-pore structure of the formed fabric, only smalladditional friction forces arise, and vacuum formation on the air sideof the second seal part 2′″″ is advantageously prevented. Therefore,penetration of abrasive particles into the actual seal region isprevented. At the same time though, ventilation of the seal is ensured.Other aspects of the seal shown in FIG. 6 are the same as thosedescribed above in connection with the FIG. 2 embodiment and so theforegoing description applies equally here. Comparable or correspondingfeatures or components of the embodiment shown in FIG. 6 are identifiedby the same reference numbers as in FIG. 2, but with the addition of afive prime (′″″) designation in FIG. 6.

The principles, preferred embodiments and other disclosed aspects havebeen described in the foregoing specification. However, the inventionwhich is intended to be protected is not to be construed as limited tothe particular embodiments disclosed. Further, the embodiments describedherein are to be regarded as illustrative rather than restrictive.Variations and changes may be made by others, and equivalents employed,without departing from the spirit of the present invention. Accordingly,it is expressly intended that all such variations, changes andequivalents which fall within the spirit and scope of the presentinvention as defined in the claims, be embraced thereby.

1. A compressor apparatus comprising: a housing containing a lubricantand a coolant; a rotatable shaft penetrating the housing; a sealadjoining the shaft to seal against leakage of the lubricant and thecoolant so that the lubricant and the coolant do not leak to outside thehousing, the seal comprising: a first seal part possessing a cylindricalsealing edge adjoining the seal and seal the shaft, the sealing edgeextending along a line which deviates from a circular shape and which isclosed in itself in a peripheral direction, the line along which thesealing edge extends is wavy, comprising several arcs; and a second sealpart with a sealing section which is adapted to adjoin the shaft andwhich is hollowly cylindrical when the sealing section adjoins properlywith an outside surface of the shaft, the sealing section comprising areturn structure for returning a fluid, the sealing section configuredto extend along the outside surface of the shaft between the first sealpart and the shaft when the sealing section properly adjoins the outsidesurface of the shaft.
 2. The compressor as claimed in claim 1, whereinthe return structure is configured as a screw thread.
 3. The compressoras claimed in claim 1, wherein the return structure comprises at leastthree grooves spaced apart in a peripheral direction.
 4. The compressoras claimed in claim 3, wherein when the sealing section properly adjoinsthe shaft, at least one of the grooves extends as an arc-shaped groove.5. The compressor as claimed in claim 4, wherein the arc-shaped groovepossesses a gradient increasing in absolute value in a direction towardthe sealing edge.
 6. The compressor as claimed in claim 3, wherein atleast one of the grooves opens to a side of the sealing edge.
 7. Thecompressor as claimed in claim 3, wherein at least two of the groovescross one another.
 8. The compressor as claimed in claim 1, wherein inan axial end region of the sealing section opposite the sealing edge,the return structure comprises a groove which extends peripherally as acircular ring groove.
 9. The compressor as claimed in claim 8, whereinthe return structure further comprises at least one additional groovewhich starts from the circular ring groove.
 10. The compressor asclaimed in one of claim 1, wherein the first seal part is made from afirst material and the second seal part is made from a second materialdifferent from the material forming the first seal part.
 11. Thecompressor as claimed in claim 10, wherein the second material ispolytetrafluorethylene (PTFE).
 12. The compressor as claimed in claim11, wherein the first material is an elastomer material.
 13. Thecompressor as claimed in claim 1, wherein the second seal part is joinedto the first seal part chemically.
 14. The compressor as claimed inclaim 1, further comprising a stiffening part, wherein the first sealpart is vulcanized to the stiffening part.
 15. The compressor as claimedin claim 14, wherein the stiffening part is made from a metal.
 16. Thecompressor as claimed in claim 1, further comprising a stiffening part,wherein the second seal part comprises a radially extending firstsurface region connected to at least one of the first seal part and thestiffening part, and a radially extending second surface region of thesecond seal part opposite the first surface region and free of contactwith the stiffening part.
 17. The compressor as claimed in claim 1,wherein an axial end region of the sealing edge of the first seal partand the sealing section of the second seal part are constructed suchthat the sealing section extends axially and is free of collision withthe sealing edge when the seal is properly installed.
 18. The compressoras claimed in claim 1, further comprising a third seal part which isadapted to surround and seal the shaft.
 19. The compressor as claimed inclaim 18, wherein the third seal part comprises a gas diffusion-capablefabric that is nonwoven.
 20. The compressor as claimed in claim 1,wherein the seal comprises an outer hollow cylindrical section, aperforated disk-like section which is connected to an axial end of theouter hollow cylindrical section and continues towards inside from theouter hollow cylindrical section, and an inner hollow cylindricalsection connected to an inside edge of the perforated-disk like sectionand extending away from the outer hollow cylindrical section.
 21. Thecompressor as claimed in claim 20, wherein the outer hollow cylindricalsection comprises a hollow cylindrical region of a stiffening part whoseouter surface is connected to a hollow-cylindrical region of the firstseal part.
 22. The compressor as claimed in claim 20, wherein theperforated-disk like section comprises a perforated-disk like region ofa stiffening part which is surrounded completely by the first seal part.23. The compressor as claimed in claim 20, wherein in theperforated-disk like section, the second seal part is connected to thefirst seal part.
 24. The compressor as claimed in claim 20, wherein theinner hollow cylindrical section comprises a hollow cylindrical regionof a stiffening part which is completely surrounded by the first sealpart.
 25. The compressor as claimed in claim 20, wherein in the innerhollow cylindrical section the first seal part forms the sealing edge.26. The compressor as claimed in claim 1, wherein the return structureis configured as at least one curvalinear groove.
 27. The compressor asclaimed in claim 26, wherein the at least one curvalinear groove isarc-shaped.
 28. The compressor as claimed in claim 1, wherein the firstseal part includes a conically shaped portion having a radially outwardsurface, the radially outward surface extending from a location of thefirst seal part which axially overlaps the sealing section of the secondseal part to a free end of the first seal part, and the radially outwardsurface being linear over the entire length of the conically shapedportion.